B738 / vehicle, London Stansted, 2023

B738 / vehicle, London Stansted, 2023

Summary

On 4 October 2023, a Boeing 737-800 which had just landed at London Stansted was turning off a taxiway to reach its allocated gate when it was hit by a ground vehicle which had been driving along a roadway parallel to the taxiway the aircraft had been using prior to beginning its turn. The collision caused structural damage to the aircraft right wing leading edge and to the vehicle and was determined to have been caused by the driver’s inattention and/or a failure to anticipate that an arriving aircraft travelling in the same direction might turn right across the roadway.

Event Details
When
04/10/2023
Event Type
GND, HF
Day/Night
Day
Flight Conditions
VMC
Flight Details
Operator
Type of Flight
Public Transport (Passenger)
Flight Origin
Intended Destination
Take-off Commenced
Yes
Flight Airborne
Yes
Flight Completed
Yes
Phase of Flight
Taxi
Location - Airport
Airport
General
Tag(s)
Airport Layout
HF
Tag(s)
Fatigue
GND
Tag(s)
Aircraft / Vehicle conflict, Both objects moving
Outcome
Damage or injury
Yes
Aircraft damage
Minor
Non-aircraft damage
Yes
Non-occupant Casualties
No
Off Airport Landing
No
Ditching
No
Causal Factor Group(s)
Group(s)
Airport Operation
Safety Recommendation(s)
Group(s)
None Made
Investigation Type
Type
Independent

Description

On 4 October 2023, a Boeing 737-800 (EI-EGD) being operated by Ryanair on a scheduled international passenger flight from Luxemburg to London Stansted as FR2861 was taxiing in at destination when it was hit by an Ambulift vehicle as it crossed a unidirectional roadway to access its parking gate in day VMC.

Investigation

An Accident Investigation was carried out by the UK Air Accident Investigation Branch (AAIB). The aircraft CVR and FDR were removed and downloaded and provided useful information. Relevant airport CCTV footage and data from the Ambulift vehicle’s external 360⁰ camera system and an internal “behaviour monitoring system” were also available. The internal system “faced to the rear of the vehicle and captured the driver’s actions and head movements before the collision”.

It was noted that the 42 year-old Boeing 737 Captain had a total of 10,803 hours flying experience which included 7,915 hours on type. The vehicle driver involved had begun working at the airport seven months prior to the accident and had obtained his airside driving permit in April 2023. He had completed training on the Bulmor SideBull Ambulift vehicle - which he was driving when he collided with the aircraft - three months prior to the accident. Since then, he had also been involved in another accident about six weeks prior to the one under investigation.

What Happened

After landing on runway 22 at Stansted, the aircraft involved had been cleared to taxi to stand D62R (see the illustration below) and had turned right from taxiway ‘J’ onto the central taxiway through Apron ‘D’ in order to reach it. Another right turn from the taxiway across the uni-directional back-of-stand roadway was then required to enter the stand. By this time, the right engine had been shut down. 

B738-vehicle-Stansted-2023-airport-layout

The airport layout in the vicinity of the accident location. [Reproduced from the Official Report]

The Ambulift vehicle involved (see below) emerged from stand D63L after completing a task there and, after the driver had checked that it was clear to do so, turned right onto the back-of-stand road to go to the driver’s next assigned task at stand 62L which was just beyond and opposite to stand D62R. The aircraft on the taxiway on the left side of roadway was directly ahead of the vehicle and was moving in the same direction at almost exactly the same speed (13 mph) as the aircraft (12 knots). The vehicle speed was well within the applicable 20 mph vehicle airside speed limit.

About 15 seconds before the collision, the First Officer had called “clear right” and four seconds later, with the speed reduced to 8 knots, the aircraft began its right turn across the back of stand roadway to reach stand D62R. Whilst driving along the roadway, “the driver’s attention appeared to have been focused through the front window with no obvious glances through the left window towards the aircraft or to the right towards the stand guidance or activity at Stand D62R”. He only appeared to notice the aircraft about 5 seconds later. He failed to give way to it and as the aircraft right wing passed over the vehicle, part of the vehicle hit the leading edge of the right wing (see the second illustration below).

B738-vehicle-Stansted-2023-vehicle

The damaged Ambulift vehicle. [Reproduced from the Official Report]

B738-vehicle-Stansted-2023-wing-damage

The impact damage caused to the right wing. [Reproduced from the Official Report]

Why It Happened

Notwithstanding the accident he had already been involved in, it appeared that the driver involved was not enjoying his job. He commented that he found driving on the airport “unnerving” due to the other vehicles and it was noted that he had “previously reported a near miss with another vehicle”. He also stated that he “felt that more time was needed for each job and that there was an unfair distribution of work”. His general view of collision risk seemed to be that it lay mainly with other vehicles and aircraft being pushed back from stand which might explain the relative lack of monitoring applied to the aircraft taxiing on his left.

The overall field of view from the Ambulift driver’s seat was assessed as good and it was concluded that there had been no obscuration of the view of the aircraft on the left or ahead.

It was noted that the potentially relevant phenomenon of “look but don’t see” errors - selective attention or “inattentional blindness” has been well researched and notably demonstrated by the classic “gorilla experiments” reported by Simons and Chabris in 1999.

It was found that the ground handler waiting to meet the flight on stand had seen that a collision was imminent and had unsuccessfully attempted to get the flight crew’s attention but by this time, their attention had moved to the stand entry guidance system and “they were concentrating on accurately parking according to that system”. The Investigation did consider that use of the STOP function of the stand entry guidance system would have been a more effective way to signal to them.

Overall, it was accepted that the environment and operational context in the area involved is challenging for all vehicle drivers with “lots of opportunities for conflict between vehicles and aircraft” which can arise from any direction. It was considered that when workload is high drivers and pilots may be fatigued and “it is not surprising that visual searches will not always be completely thorough, especially considering phenomena such as inattentional blindness". It was noted that the airport authority intends to review the current road layout and design to see if any improvements can be made without introducing new risks.

The narrative Conclusion of the Investigation was as follows:    

A Bulmor SideBull OMNI 135 vehicle collided with EI-EGD because the vehicle driver did not see the aircraft or did not anticipate it would turn onto stand. The driver may have experienced inattentional blindness and his performance may have been reduced by the fast operating tempo, high workload and task related fatigue. The stand and road layout in the area created the potential for conflict between vehicles and aircraft to arise from any direction.

Safety Action was noted to have been taken by both the vehicle operator and the airport authority. Both issued Safety Notices to airport drivers regarding safe driving practices. The Airport notice drew attention to clues that drivers can use to recognise that an aircraft would soon be turning on to stand, such as the presence of personnel and equipment at the head of stand and the activation of the stand guidance system.

The Final Report of the Investigation was published on 24 August 2024. No Safety Recommendations were made.

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